OK, so I'm interested in the Torii MKIV for a rig driving Harbeth P3ESR. I have only one stumbling point... To have all the functionality I desire (in a home office) I would need either a preamp output (to connect to an external headphone amp) or a headphone 1/4" jack itself. That is, I want both my sources (DAC and Turntable) connected to both of my transducers (speakers and headphones).

Could this be accommodated?

Thanks!

Thank you for asking! Two problems... MKIV has too much power for good headphone jack performance and too little power for Harbeth speakers which when converted to a 1 watt / 1 meter sensitivity are about 81dB. That's 10dB below the recommended minimum. Below is the performance with the Harbeth/Torii MK IV combination.

An alternative approach would be using the 4 watt Mini-Torii with headphone jack paired with the DM945/6 speakers.

1 watt = 94dB @ a distance of 1 meter2 watts = 97dB4 watts = 100dB

The last Mini Torii that went out replaced an Audio Note 300B amplifier driving similarly efficient Audio Note speakers and the owner is quite happy. The DM945/6 speakers are over twice as fast as the Harbeth with the same silky smooth tone, so they too could be an upgrade.

Hi,Some questions about this thread, if I may?1) What is meant by "fast" ?2) I have a pair of B&W 802 D ( the version just superceded ) with a sensitivity of 90 db. Used in a room approx 20 ft long x 12 ft wide, vaulted ceiling. I rarely play above 1/4 volume with a Bryston 3B NRB 120 wpc. AR LS15 preamp.

If I understand your amp selection chart the Torii Jr or Mk 4 would be sufficient.

However, B&W recommend a minimum of 50 wpc? I realize I am likely only using 15 to 20 wpc during most listening, so, why need a 50 to 500 wpc?

One of my first stereo systems was Telefunken V250 25 wpc class A amp, into 4 ohms, driving a pair of very efficient Telefunken speakers.

Fast is the time it takes for the speaker cone to change direction. The higher the mass of the cone, the harder it will be to stop it from moving in one direction and start it moving in the opposite direction. Efficient speakers have cones that are low in mass, in extreme cases almost 10 times lower.

A high mass cone requires an amplifier with a lot of power and damping (negative feedback) to help control the cone from overshoot.

There are only two reasons for high mass speakers cones.... makes the driver resonate in a small box and has less peaky response or is more immune to colorations from the enclosure due to the the damping effect of thicker cone material. It's the easy way out.

Part of the speaker power recommendation could come from losses in the crossover that are hard to resolve on paper, and or the damping factor needed to keep the speaker from sounding muddy in the bass. This damping factor is typically found in push-pull amps with negative feedback in the 50watt or higher range.

1) extremely good reviews, on both private sites and "advertiser driven"

2) a damping factor of 4000

3) comments from others who have my exact speakers in their system, and have experimented with numerous amps

I can say that I am listening to my collection of music, some of which I bought on vinyl over 40 years ago, and I hear background instruments and voices that are new to me. The voices often surprise me with their lifelike sound, and I can easily understand many lyrics that, on further thought, I realize I could not understand due unless I focused.

I assume the damping factor is a major factor.

I will be biwiring my speakers next, I think I have picked the low hanging fruit..

I rarely get it above 1/4 volume on my preamp. However, the sound quality and detail I am getting at very low amperage is amazing. My speakers are known for being difficult to drive.

In conversations with other owners ( after I bought them ) I found out that many people use 400 wpc or even 500 wpc. I heard them with a McKintosh 602 amp, 300wpc, and the dealer told me I really needed a more powerful amp!

Its sort of like using a big block engine vs a small block engine. The torque of the big block just make towing work.

If you have extremely sensitive speakers, you can use a small amp. My first stereo was a Telefunken, class A amp, V250 model. It drove my Telefunken speakers and sounded amazing. All with 25 wpc..